Concentration of slimes by flotation



Patented Mar. I1, 1927.

f GJLEE'RT A. EEAGG, or EAsr ORANGE, .NEW JERSEY; Assiduo PATENT OFFICE.

n. To METALS REcovERY COMPANY,- OF .NEW YORK,v Ne' Y., A CORPORATION OF MAINE.

CONCENTRATION OF SLIMES BY FL OTA.TION

Application liled September 2,8, 1926. Serial No. 138,180.

This `invention relates to the concentration of slimesby flotation, and has for its object the provision of certain improvements` in cuncentrating s'limes by flotation.

. In ore milling operations, it is frequently the practicelto deslime ancre pulp in order to .separate the very finely divided solid,

particles from coarsersolid particles. The very fine particles often interfere with the separative treatmentsto which coarser particles are amenable, and such cases it is therefore advantageous to carry out the desliming operation; In general,V it is customary to speak of that portion of the pulp containing thevery fine oreparticles and resulting from the desliming operation as slimes., y Y t The desliming operation is ordinarilyin the nature of a classifying treatment and the slimes then usually contain approximately the same proportions of the mineral constituents as present in the ore pulp prior to desliming. The slimes, while amenable to flotation treatment, dpossess certain physical characteristics 'that make thea plication of flotation concentration there dliicult. and in some instances uneconomical. :Heretofore no entirely satisfactory method of concentrating slimes by-flotation has been available. This is more particularly true Vwhere atrtcmpts have'been'made to usethe so-'called 'non-oleaginous chemical fiotati'on agents such as typified by thiocarbanilid and 'Xa'n-H slimes can be advantageously promoted by thate.v l

I have discovered that the flotation of npreagitation of the slimes with an alkaline agent such as lime. Theconditioning action of thelime on the sulfide mineral particles in the slime appears to require both time and vigorous agitation. This is probably due to the fact that the/film 'coatings adsorbed on or otherwise attachedto the sulfide mineral particles' tenaciously adhere to the particles and are difficultly removed o1 otherwise con-4 ditioned by the lime treatment. In practice, I have secured excellent results by vigorous mechanical agitation for a period of. from 5 to 2O minutes. y

As a result of my experiments and investigations, VI have found that the conditioningof the slime by' preag'itation with lime is essential to the successful iiotation vof the slime with chemical flotation agents-such as thiocarbanilid and Xanthate.

'preagitators y After the condi-l .tioningl of the" slime with lime'has been collnl pleted, the mineral-collecting agent such as tlnocarbanilid or Xanthaie and the frothing agent, such as pine oil, are added to the slime and the flotation operation is then conducted 1n pneumatic flotation( apparatus,v such,. for. example, as the Callovv or subaeration machines. y f

In addition to the conditioning treatment, I have found itV essential, using chemical reagents, to conduct the flotation operation in machines giving a relatively high degree of aeration. This appears to be due to the fact that more air `is required in thefiotation of the slime, using chemical reagents, than isavailable in liotation machines -of the mey chan'ical agitation. type.- I prefer to carry ores, the ore is first subjected `to coarse crushing and is then jiggedftoseparate a finished concentrateand a tailing. The tailing is subjected to further grinding and the ground' tailings are then classified or de-` slimed in appropriate classifiers, the overflow of the classifiers constituting the slimes to which my present invention relates. The slimes contain about 3 to 4% copper. From to-95% of the solid particles in the slime,

will be through 200 mesh, while less than/A., one percent will be on 1-00 mesh, the remaining to V9% being between 100 and 200 mesh. The slime usually` contains from 'l0 to 14% solids.

The single figure of the accompanying drawing diagrammatically A illustrates my present preferred arrangement of apparaw for practicing. the invention. The

drawing will be understood by the legends thereon `taken in conjunction 'With the fo1- `lowing description.

The slimeis conducted in any appropriate manner to the conditioning apparatus or This apparatus may advantageously consist of four agitation compartments ,of Y a standard minerals separation machine. Thes'pitzkastens belonging to these agitation compartments may be blocked vided with the usual olf, or removed. The slime flows through the four agitation compartments in series. .Narrow vertical baflies just submerged in the slime prevent itfrom whirling with the agitators and vortexing in each agitation compartment. The reason for preventing the vortexing is that it lowers the volume of pulp being agitated in each compartment and consequently lessens the time of agitation. The agitation compartments are about three feet square and the pulp is about three feet deep inv each. compartment. ment of the conditioning apparatus is procruciform agitator 2l inches in diameter and rotating at 240 Ii. P. M. Lime and thiocarbanilid are added to the slime as it vflows into the. first cell or compartment of the pre-agitator. Each compartmentofthe preagitator has a conditioning capacity of about 12 tons of slime per 2t hours. Where more than about 12 tous of slime per 24 hours are put through each compartment or cell of the preagitator, the copper content of the final tailings increases, whereas when r12 tons or less per 2l hours per cell or compartment are treated the copper content of the tailings is not materially lowered. This rate of flouT of the slimes through the preagitator gives' about 15 minutes preagitation of the slime with the lime. l

I have found that thetemperature of the slime should be around 70 F. for the best results in the subsequent to the preagitators Ais substantially less than 70 F., I prefer to heat the slime as, for example, by introducing steam into the first cell or compartment of theV preagitator in -amount sufficient to raise the temperature of the slime to about F. Any other convenient means may, of course, be employed for regulating the temperature of the slime to give the optimum results in the flotation operation. A.

The conditioned slime is now conducted to pneumatic iiotation apparatus. In my present preferred practice, this apparatus consistsof twoCallow flotation machines arranged to operate as' a cleaner and a rougher respectively.. The slime first enters the cleaner and a finished froth concentrate is taken off this machine. lThe tailings from' the cleaner constitute the feed of the rougher. The overflow froth from the rougher joins lthe original slime feed to the cleaner -and the pulp discharged from .the rouffherinay be sent to waste as' final tailings. thioca'rbanilid and orthotoluidin (the socalled T--T mixture containing approximately 20% of thiocarbanilid) isadded to the slime feed as it drops into the cleaner. A frothing agent, such as steam-distilled pineoil, is added to the pulp discharging from the cleaner and going into the rougher.

The following specific figures are given flotation operation. Where the temperature of the slime as fed.

.e -niixture of Leraren by way. of example to illustrate the forego.- ing preferred practice of the invention with Anaconda slimes. In the conditioning operation, about 10 pounds of lime and about 0.25 pounds of thiocarbanilid are used per tou of solidsin the slime. About 0.50 pounds of the T-T mixture per ton of solids is added to the slime feed to the cleaner or initial flotation machine and about 0.06 pounds of steam distilled pine oil per ton of solids is added to the feed to the rougher or secondary flotation machine. 'lhe original slime assayed 3.06% copper, of which 0.30% was oxidized copper. rl`he final concentrate assayed 14.86% copper and 33.3% insoluble. The final tailings assayed 0.30/L copper, of which 0.19% was oxidized copper. The tailings from the cleaner or primary. flotation machine assayed 0.8027(y copper.

During another run on Anaconda slimes, as saying 3.21% copper of which 0,-l0% was oxidized copper, the finalv concentrate assayed 15,35% copper and 36.50% insoluble, and the final tailings 'assayed 0.37% copper of which 0.23%- was oxidized copper. this run 10.8 pounds of lime, 0.36 pounds of thiocarbani'lid, 0.52 pounds of T-T mixture and 0.01 pounds of No. 5 steam-distilled pine oil were used per ton of solids in the slime,

There potassium or sodium Xanthate Ais used as the mineral-collecting agent, good .results have been secured with about T pounds of lime, 0.8 pounds of the Xanthate, 0.04 pounds of steam-distilled pine oil and 0.16 pounds of No. 11 crude -pine oil per ton of solids in the slime. Xanthate is dissolved in n'ater and the solution added to the later cells or compartments of the preagitator. The steam-distilled pine oil is added to the secondary fiotation feed andthe No. 11 crude pine oil to the primary fiotation feed. With a slime feed assaying 4.24% copper a nal concentrate assaying 111.97% copper was obtained. The final tailings contained 0.26%- copper (0.19% oxidized copper). f

As a result of my' experiments and in vestiga-tions, I'hare found that ore slimes, such as Anaconda shines, can not-'be satisfactorily eoncentratcdby fiotation in niachines ofthe agitation froth type as ordinarily operated using` chemical mineral-collecting agents such as thiocarbanilid and Xanthate. I hare moreover found that such slimes, using chemical `mineral-collccting agents, cannot be satisfactorily concentrated by flotation 1n pneumatic flotation machines,

in the absence of the conditioning treatment hereinbefore prescribed. My investigations have indicated that both agitation and aeration are essential for the successful treatn'ient by flotation of ore slimes when using .chemical mineral-collecting agents.

Anaconda slimes have heretofore been concentrated lay-flotation in standard minlos ' the4 s liine.

erals separation machines using'` kerosene acid sludge and sulfuric acid. .My present invention provides an improved method of treating these slimes by flotation in which use may be made of chemical mineral-collecting agents whereby a higher grade ofconcentrate and lower tailings are obtained. In its broad aspect the present invention involves the combination of three features namely, (l) conditioning of the slime vby preagitation with lime (2) pneumatic flotation of, the conditioned slimein the presence of a- `non-oleaginois mineral-collecting agent. 15

' ore exposes fresh ore surfaces and the desired action of the lime is thereby promoted. rlhe solid particles in an ore slime to which my invention relates are. for the most part;

of a size that will pass lthrougha 200 mesh screen, and by .most part l mean or more, of the total solids present in the slime,`

While the solid particles that'will remain on a l0() mesh-screen will be relatively small, usually less than 5% of the total solids in The solid particles-inan orc slime are, therefore, already a'sfinelyv coinminuted as practicable, and ythere is, accordingly, iiooccasi'on to subject the slime to a grinding operation, and the violent agitation to Which thc slime is subjected intlie conditioning treatment of the invent-ion 'does not involve any substantial com'minu.

tion of the ore I claim: 1. The improvement in the treatment by flotation of ore slimes in which the solid parparticles in the slime.

ticles are for the most part of a size that Will.

pass through 20() mesh which comprises subjecting the slime to violent agitation with lime for a sufficient length of time to condition the sulfide minerals in the slime for subse-`' tion with lime for a sufficient length f time i to condition the sulfide minerals inthe slime forsubsequent flotation, a part at least of said conditioning -treatment being carried out in the-,presence of non-oleaginous min-V eral-collecting agent, and then' subjecting. thesofconditioncd slime to a pneumatic flotation operat-ion in the presence of' a nonoleaginous mineral-collecting agent.

8. Tlfe improvement in the'treatinent by flotation of orc sliines in which the solid particles are for the most part ofl a size that will pass through 200 mesh, which comprises subjecting the slime to violent agitation with linie for a sufficient length of timeV to condition the sulfide minerals in the Slime for subsequent flotation, subjecting the soi conditioned slime to an initial pneumatic y flotation operation .in the pi'esenceof' a non.- oleaginous mineral-collecting agent and thereby obtaining a final froth concentrate, subjecting the tailings from said initial fiotation operation to a secondary pneumatic flotation o eration, and retreating the froth overflow rom said secondary flotationoperation in said initial flotation operation.

4. The improvement in' the treatment by flotation -of oie slimcs in which lthe solidV particles are for the most part of a size that will pass through 200 mesh, .which comprises subjectinrr the slime to'violent agita. tion with lime for a sufficient length of time for subsequent flotation, a part at least of said conditioning treatment being carried out in the presence of'a noii-oleagiiious mineral-collecting agent, subjecting the so-conditioned 'slime to an initial pneumatic flota-l tion operation in the `presence of a non-oleaginous mineral-collecting .agent and thereby obtaining a final frothconcentrate,.sub

Vto condition the sulfide minerals iii the slin'ieI jecting the tailings from said initial flotavtion operation to a: secoiiolarj7 pneumatic flotation operation, and retreating` the froth l overflow from said secondary flotation opera-V tion in said initial flotation operation.

5. The improvement in the treatment b v flotation of .ore slinies in which the solid particles are for the most part of'a size vthat Will pass through 200 mesh, which comprises subjecting the slime to violentv agitation with lll) lime for a sufficient length of time to condition .the sulfide minerals in the slime for subsequent flotation, subjecting the so-conditioned slime to aninitial pneumatic flotation operation in the presence of a non-oleaginous mineral-collecting agent and thereby obtaining a final froth concentrate,- subjecting the tailings from said initial flotation .Operation together with an added frothing agent to a secondary pneumatic flotation operation, and retreatin the froth overflow from said secondary otation operationin said initial flotation operation.

6. The improvement 1in the treatment by' flotation "of oreslimes in which the solid particles are4 for the most part of a Vsize that will pass through 200 mesh, which comprises subjecting the slime to'violent agitation with lime fora sufficient length of time to condition the sulfide minerals in the slime for'` subsequent flotation, a part -at least of said conditioning treatment beingcarried out in the presence of a non-oleaginous mineralcollecting agent, subjecting the so-condi tioned slime to an initial pneumatic flotation operation in the presence' of a non-oleaginous 'mineral-collecting agent and thereby obtaining a final froth Concentrate, subjecting the tailings from said initial flotation loperation y together With'an added frothing agent to a secondary pneumatic flotation operation, and

re-treating the froth overflofv from said secondary flotation operation in said -initial flotation operation. y

7.' The improvement in the treatment by flotation of ore slimes in which the solid particles are for the most part ofa size that will pass through 200 mesh, which comprises subjecting the slime to violent agitation with lime for a sufficient length of time to condiv tion the sulfide minerals in the slime for Y as ' subsequent flotation, u V

'conditioning treatment being carried out in subsequent flotation, a part atleast of said conditioning treatment' being carried out in the presence of thiocarbanilid, and then subjecting the so-conditioned slime to a'pueumatic flotation operation in the piesence of thiocarbai'iilid and ort-hotolu'idiii.

8. rI`he improvement in the treatment by flotation of ore slimes 'in which the solid particles are for the most part of a size that Will pass through 200h mesh, which comprises Y subjecting the sl imevto violent lime for a sufficient length of time to condif tion the sulfide minerals in the slime for a part atleast of said agitation With flotation of ore `slimes in which the solid particles are for the most part of a size that will. pass through 200 mesh, which comprises subjecting the slime to violent agitation With lime for a sufficient length of time to condition the sulfide minerals in the slime for subsequent flotation, a part at least of said conditioning treatment being carried out int-the vpresence of thiocarbanilid, subjecting thereoconditioned vslime to an -initial pneumatic Vflotation operation in the presence of thiocarbani'lidand orthotoluidin and thereby obtaininga final froth concentrate, subjecting the tailings from said initial flotation operation together With. an added frothing agent to a secondary pneumatic flota-tion operation, and retreating the froth overflow from said secondary flotation op-eration in said initial flotation operation. A

-10. The improvement inthetreatment by flotation of ore slimes in which the solid.

particles are for the most part of a size that will passthrough 200 mesh,`which comprises subjecting the slime to violent agitation with lime for a sullicient length of time to condition the sulfide minerals in the sli-me for subsequent flotation, and then subjecting the soconditioned slime in the presence of' a nonoleaginous mineral-collecting agent to a flotation operation giving a relatively high degree of aeration.

ll. The improvement in the treatment by flotation of' ore slim-es in which the solid particles are for the most part. of a size that Will pass through 200 mesh, ,which comprises subjecting'the slime to violent agitation With lime for a sufficient length of time to condition the sulfide minerals in the slime. for subsequent flotation, a part at least of said convditioning treatment being carried out in' the presence of a non-oleaginous mineral-collecting agent, and then subjecting the iso-condi! tioned slim-e in the presence of" a non-oleaginous mineral-collecting agent to a flotation operation giving a relatively high degree of aeration. y

In testimony whereof I affix my signature.;

" GILBERT A. BRAGG. 

